Originally Posted by
williaty
Between two cogs in the cassette. The gaps in the current 8-speed cassette are 13-16% right now and I just don't like it. Yes, I have a very narrow range of cadence and force that I'm comfortable in. Prior knee injuries have left me unable to exert much pressure on the pedals, so I have to spin everything basically at the max I can without starting to bounce.
This sounds like something you'll have to experiment with. Either you get a closer ratio 8spd cassette and get exactly the gear gaps you want with low and high gears compromised somewhat or you turn over the drive train to 10spd.
I do find your need to maintain a particular output and cadence that is so specific as to require such a closely spaced gear cluster(probably closer than racers in the 60's) in somewhat contradiction to the need to reduce aggravating knee injuries. Aggravating knee injuries are more likely to come from pushing to a particular max effort than dialing back that effort to meet the gear that's 69" instead of 72". In other words the terrain ends up varying more than the discrete number of gears and you'll end up having to shift out of the ideal 10speed cog because the wind went up 5% or the grade went up 1%. Simply reducing your effort to match your prefered cadence would do the same thing.
Is it that you want the closely spaced gears to occur with the same chainring so you don't have to hunt for the other combinations on the other chainring?
Check out a 13-26 8spd cassette with 22/32/44 crankset on 700x35 wheels. A 22-92 gear range of closely spaced gears. If you have knee problems you probably aren't putting out the hp. that can utilize 96"+ gears so you can enjoy a closer spaced mid range of gears.